Acetaminophen And Codeine and Benzthiazide: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jun 30, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
Benzthiazide
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
You've been prescribed a water pill (benzthiazide) along with a pain medicine that contains codeine. Water pills help your body get rid of extra fluid and can help lower blood pressure. The concern here is that codeine may trigger your body to hold onto more water, which could make the water pill work a little less well than expected.
The good news is that this is based mostly on theory, not strong real-world proof. Your care team can easily keep an eye on things like your blood pressure and swelling, and adjust your water pill dose if needed. Keep taking both as prescribed and let your doctor or pharmacist know if you notice more swelling or rising blood pressure.
Effect: Codeine may reduce the diuretic and antihypertensive efficacy of benzthiazide, a thiazide diuretic.
Mechanism: Opioid-mediated stimulation of antidiuretic hormone (ADH) release promotes water retention, opposing the diuretic's pharmacodynamic effect. This is a PD interaction, not a metabolic one.
Evidence/onset: Theoretical; onset unspecified. Magnitude not quantified.
- Monitor diuresis, edema, weight, and blood pressure.
- Diuretic dose may be adjusted and individualized as clinically indicated.
- Effect is dose- and duration-dependent with opioid exposure.
The acetaminophen component is not implicated in this interaction.
What happens
Reduced diuretic efficacy
Interaction Deep Dive
Concomitant use of codeine with diuretics may reduce the efficacy of diuretics by inducing the release of anti-diuretic hormone. Monitor patients for signs of diminished diuresis and/or effects on blood pressure and increase the dosage of the diuretic as needed1.
Why it happens (mechanism)
Increased opioid-mediated release of antidiuretic hormone
How to manage this interaction
Keep taking both medications as prescribed unless your care team tells you otherwise. This interaction can be managed with routine follow-up.
- Your team may watch more closely for signs the water pill isn't working as well, such as more swelling, weight gain, or higher blood pressure.
- If needed, your diuretic dose may be adjusted and individualized by your care team.
- Let your pharmacist or prescriber know if you notice increased puffiness in your legs, rapid weight gain, or blood pressure readings creeping up.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Benzthiazide together?
Codeine may slightly weaken how well your water pill (benzthiazide) removes fluid and controls blood pressure, so watch for swelling or rising blood pressure and let your care team adjust the dose if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Benzthiazide interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Acetaminophen And Codeine and Benzthiazide interaction managed?
Keep taking both medications as prescribed unless your care team tells you otherwise. This interaction can be managed with routine follow-up. Your team may watch more closely for signs the water pill isn't working as well, such as more swelling, weight gain, or higher blood pressure. If needed, your diuretic dose may be adjusted and individualized by your care team. Let your pharmacist or prescrib… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Acetaminophen And Codeine or Benzthiazide need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: CARISOPRODOL, ASPIRIN, CODEINE PHOSPHATE oral tablets, carisoprodol, aspirin, codeine phosphate oral tablets. Ingenus Pharmaceuticals LLC (per DailyMed), Orlando, FL, 2021. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Benzthiazide
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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